Skin’s secret strength shields against puncture damage

Across the natural world, puncture threats are nearly unavoidable. From animal fangs to plant thorns, nature is full of sharp tools capable of breaking through many layers of defense.

Surprisingly, the skin that covers many animals – including pigs and humans – has its unique way of mitigating these potentially harmful occurrences.

Skin reduces internal damage

In a recent study, researchers at the University of Illinois Urbana-Champaign discovered that our skin – that thin, stretchy layer wrapping our bodies – is not just an exterior shell.

It plays an active role in lessening the internal damage when punctured, and it does so even better than synthetic materials designed to imitate it.

This attribute largely comes from skin’s ability to redistribute the energy from a puncturing object, thereby minimizing harm to the deeper tissues. The team embarked on a journey to decipher the secret of skin’s remarkable resilience.

“You’ll find things that puncture across multiple kinds of organisms – vertebrates, invertebrates, plants, and fungi – at all scales and different dynamic regimes, so fangs, claws, spines, stingers, and other long, sharp implements,” said Professor Philip Anderson, who led the study.

The dynamics of puncture

Understanding the dynamics of puncture involves studying a myriad of variables – the speed, shape, and sharpness of the puncturing object, and the properties of the target material.

The team began by observing the basic elements of puncture, using 3D-printed cones of varying shapes and sharpness levels, and silicone gels of different densities. When this groundwork was laid, they advanced their investigation to actual biological materials.

Skin protects from puncture damage

With a series of experiments, the team examined the “puncturability” of pork slabs with and without skin and compared these with synthetic imitations. The synthetic analogue was a silicone gel approximating the rigidity of animal blubber and a thinner, higher-rigidity gel representing skin.

“Using a combination of dynamic puncture experiments and theoretical modeling, we examined the puncture resistance of both natural skin tissues and synthetic bilayer tissue-mimicking materials,” noted Bingyang Zhang, postdoctoral researcher at the University of Illinois Urbana-Champaign.

“We found that, despite its thinness, pig skin attached to underlying tissue reduced damage from puncture by about 60% at slower speeds and 73% at higher speeds compared with the same pig tissue without skin.”

In contrast, synthetic skin offered less protection, reducing the damage to the underlying gel by less than 40% at slower speeds and less than 30% at higher speeds.

Unique composition of skin

The researchers hypothesize the superior performance of natural skin could be attributed to its structure being primarily composed of collagen fibers. These fibers are interweaved, offering resistance even when some are broken.

Additionally, the breakage of the collagen fibers dissipates some of the energy from the puncturing object, thus slowing it down and reducing its capacity to penetrate deeper into the tissue. Synthetic materials lack this crucial trait.

Skin redistributes force

The study showed that our skin is not just our body’s wrapping; it’s an active shield that remarkably redistributes force and dissipates energy.

“We also learned a great deal about how synthetic materials, while useful in many scenarios, still fall short in replicating these complex biological functions,” said Zhang.

This research shines new light on the wonders of nature and the incredible ways our bodies protect us from harm, even in ways we’ve never realized.

As scientists continue to uncover these mysteries, we can only marvel at the extraordinary complexity and functionality of such seemingly simple things – like the skin we live in.

Innovations in flexibility and durability

The insights from this study have potential applications far beyond understanding natural defenses.

Medical devices, wound dressings, and protective equipment could all benefit from mimicking the puncture-resistant properties of skin.

By incorporating collagen-like fibers or designing materials that can distribute puncture energy, manufacturers may enhance the safety and durability of products like surgical gloves, body armor, or even artificial skin grafts.

This knowledge could ultimately inspire innovations in fields where both flexibility and durability are essential, bringing human-made materials a step closer to the natural efficiency seen in skin.

The study is published in the journal Journal of The Royal Society Interface.

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